Problem: Which of the following numbers is a factor of 188? ${4,7,8,10,11}$
Solution: By definition, a factor of a number will divide evenly into that number. We can start by dividing $188$ by each of our answer choices. $188 \div 4 = 47$ $188 \div 7 = 26\text{ R }6$ $188 \div 8 = 23\text{ R }4$ $188 \div 10 = 18\text{ R }8$ $188 \div 11 = 17\text{ R }1$ The only answer choice that divides into $188$ with no remainder is $4$ $ 47$ $4$ $188$ We can check our answer by looking at the prime factorization of both numbers. Notice that the prime factors of $4$ are contained within the prime factors of $188$ $188 = 2\times2\times47 4 = 2\times2$ Therefore the only factor of $188$ out of our choices is $4$. We can say that $188$ is divisible by $4$.